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➤微信公众号：山青咏芝（let_us_code）
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Given a matrix mat where every row is sorted in increasing order, return the smallest common element in all rows.
If there is no common element, return -1.
Example 1:
Input: mat = [[1,2,3,4,5],[2,4,5,8,10],[3,5,7,9,11],[1,3,5,7,9]] Output: 5
Constraints:
1 <= mat.length, mat[i].length <= 5001 <= mat[i][j] <= 10^4mat[i]is sorted in increasing order.
给你一个矩阵 mat，其中每一行的元素都已经按 递增 顺序排好了。请你帮忙找出在所有这些行中 最小的公共元素。
如果矩阵中没有这样的公共元素，就请返回 -1。
示例：
输入：mat = [[1,2,3,4,5],[2,4,5,8,10],[3,5,7,9,11],[1,3,5,7,9]] 输出：5
提示：
1 <= mat.length, mat[i].length <= 5001 <= mat[i][j] <= 10^4mat[i]已按递增顺序排列。
1 class Solution { 2 func smallestCommonElement(_ mat: [[Int]]) -> Int { 3 let n:Int = mat.count 4 var ps:[Int] = [Int](repeating:0,count:n) 5 let m:Int = mat[0].count 6 outer: 7 for i in 0..<m 8 { 9 for j in 1..<n 10 { 11 while(ps[j] < m && mat[j][ps[j]] < mat[0][i]) 12 { 13 ps[j] += 1 14 } 15 if ps[j] < m && mat[j][ps[j]] == mat[0][i] 16 { 17 continue 18 } 19 else 20 { 21 continue outer 22 } 23 } 24 return mat[0][i] 25 } 26 return -1 27 } 28 }